چكيده لاتين :
Subclinical mastitis is a serious dairy herd problem. Many infected cows contribute to the low production and high somatic cell count (SCC), which reduce milk quality premiums. Bulk-tank milk analysis is a useful tool for improving milk quality in a dairy operation. A cross-sectional survey of 57 dairy farms in the suburb of Tehran was carried out with sampling in 3 consecutive intervals. Milk samples were cultured and divided in four groups based on total bacterial count (TBC) and SCC. Twenty six samples had TBC<50000 and SCC>250000 (group 1), 18 samples had TBC>50000 and SCC>250000 (group 2), 7 samples had TBC<50000 and SCC< 250000 (group 3) and 6 samples had TBC> 50000 and SCC<250000 (group 4). The microorganisms isolated from the 4 groups in order 1-4 were: Streptococcus agalactiae (4, 0, 0 and 2), Staphylococcus aureus (7, 6, 3 and 1 in 4), high level of Streptococcus uberis (4, 2, 3 and 3 in 4), Streptococcus dysgalactiae (3, 5,4 and 1), high level Escherichia coli (23, 16, 5 and 4), high level Klebsiella species (2, 1,0 and 0), high level Enterobacter (3, 2, 4 and 0), high level Citrobacter (10, 13, 5 and 2), high level Coagulase-negative Staphylococcus (21, 12, 5 and 6), Pseudomonas aerogenese (13, 10, 2 and 5), Proteus (6, 1, 2 and 0), Serratia marcescens (2, 2, 0 and 2), Nocardia astroides (3, 0, 1 and 1), Listeria monocytogenes (2, 1, 1 and 0) and Edwardsiella tarda (0, 1, 1 and 0). In this study except Prototheca and Bacillus, other above mentioned pathogens were isolated in the culture, presence of most these pathogens in BTM indicate that there are problems in our mastitis control programs in our dairy farms. The present screening study may help to design mastitis prevention protocols in the future. Islamic.Azad. Univ., Garmsar Branch. 4,2:94-98,2008.
